Amazon Kindle (Paperwhite) not recognized
Solution 1:
I suggest trying different cables, it finally solved my problem in the end after having lost some time (Paperwhite connecting to Ubuntu Xenial).
Store-bought cables laying around appeared to only be capable of charging the device. A Huawei P9 lite original cable was the one that finally made the connection.
Solution 2:
I've stumbled upon the same problem. After installing mtpfs all worked fine.
sudo apt-get install mtpfs
Don't forget to remove and insert the usb cable again.
FYI: Mine is a Kindle Touch.